Golf mk5 boot release fuse?

[Flash2]

Well done Mike. Sorted without any expensive diagnostic stuff. Always worth trying the simple things first.
And thanks for posting your fix. That may benefit someone else who gets the same problem in the future.

Good job!

Jim.

[bigmedsi]

Sorry to revive an old topic but my mk5 boot is doing a similar thing - except some days it will work and some days it wont. I've only had it for a month and the garage I bought it from had the boot switch fixed before I bought it so I took it back there and they checked it all out from the switch to the wires running through the car to the central module and couldn't find anything.

They just recommended I take it to a VW garage and get them to do some diagnostics on the central module but I was wondering if anyone here had any ideas?

Everything else on the car is working perfectly it's just this electric boot switch (again it opens on the manual latch inside). I've never really messed around with the electronics in a car (have only had mk2s up until now) so not really sure where to start with the helpful posts on the previous page :S)

I was also wondering, I've heard you can reprogram the key fob to open the boot, could that be a work around option?

Thanks in advance!

[bob b]

I had a couple of puzzling faults on my Golf. The rear fog lamp wasn't working and the interior boot lamp was u/s. The usual items were investigated, fuses, bulbs, fittings etc. It was the wiring damaged in the rubber 'concertina'' boot between the tailgate and the car body. As the damage was hidden in the centre of the rubber boot, it took me quite a while to find it. The loom is obviously too short, and the opening and shutting of the tailgate over time has 'worked' the cables and caused the damage.

I destroyed the rubber boot to get to the damage and have soldered short lengths of cable into the wiring loom by way of extensions. Fortunately my local scrap yard has a mk5 Golf which yielded a replacement boot. I attach a photograph of the damage as it may help someone in future.

Image00001.jpg

[bob b]

I should have added that the cables to the boot lamp and rear fog were completely broken, but you can see that the insulation to other cables has been damaged and exposes the copper wire. They were problems waiting to develope !

[Crasher]

As I have been seeing this since about 1987 on the Golf 2 (oddly I have never seen this on a Golf 1 1974 to 2012) you would think VAG would have either worked out a cable that did not fatigue or gone back to using contact pads and plungers like they did on the Audi 50/Polo 1 from 1974.

[obs]

Error is: Trunk boot won't open. Not by outside handle or key.

Golf MK5 2007 with less than 3000 miles. Error was there when I bought it. I see someone have had a look at it and lock mechanism locks new.

Done this
Checked fuses all, are ok.
Can mechanically open trunk from inside with emergency open and dismantled the cover to trunk to get full access.
Took out the lock to have a look at it mechanically it's ok.
Measured voltage without really know what I'm looking for voltage is there but low. 10,3v between pin 1 and 4. 11.5v between 2 and 3.
12V in on the outside handle to the trunk.

Also thanks to this awesome forum I checked for cable wear between trunk and body top left and one white thicker cable have plastic damaged but all copper is still there. No other cables have apparent damage.

I replaced the lock with a used one from a shop for 25 pounds but did not help.

So Voltage is low I guess with apron 15% is this the problem?
Should I remove the handle on the outside and look for dirt att microswitch inside handle? But should not the remote key still open trunk if it's the handle itself that is broken? Have not had a Golf before so don't know how the remote really works.

What can it be and what else to test and look for? Thought you all already gave me the answer before I got stuck.

[Flash2]

Measured voltage without really know what I'm looking for voltage is there but low. 10,3v between pin 1 and 4. 11.5v between 2 and 3.
12V in on the outside handle to the trunk.

You would only have voltage to the unlock actuator while it was being activated by the control module. It would be a short 12V pulse on one of the wires. But I think it's safe to assume the 12V pulse isn't present since both locks you've tried don't unlock.

But should not the remote key still open trunk if it's the handle itself that is broken?

Correct, so I wouldn't bother looking at the handle.

What can it be and what else to test and look for?

It could be a break in the wire, or a faulty control module. Or possibly someone has altered the coding of the control module. That's something we always need to be mindful of with VWs.

[obs]

As you say most likely wire fault. When both handle and remote is gone. Can that really be a coding issue? Then I got to go to the VW shop. I can't see any obvious problems though all is super clean and neat. Except the small cut in plastic on one wire. Usually by bending around a bit you can feel a problem on a cable. Look at them closely. I'm an electrical engineer but have not practiced since 1992.

Do you know what the 4 different pins should read for actuator? Can I force test it with 12V? I got power but as I wrote it's a bit low so that might be the issue too.

[Flash2]

I don't really know for sure whether it could be a coding issue or not, tbh.

A force test with 12V is one of the first things I'd do. But I'd feed the 12V in at the control module. If it unlocked you'd instantly know that the wiring between the module and the lock was good.

I don't know what voltages you should get on all the pins off the top of my head. I'd expect the pin with 11.5V to be the boot light switch though. And if you have a brown wire, that will almost certainly be the earth/ground. So linking the 11.5V pin to the earth should make the boot light switch on.

Just a though.....does the rear washer & wiper work?

[obs]

<I don't really know for sure whether it could be a coding issue or not, tbh.
Ok then I wait with this. Should think handle still would work if it is a coding issue. Don't think it's a VW shop that have had a look in the past. Clips missing and the 'new lock' itself was mounted a bit of. I swapped it though for a used one on from a 6000 miles car and that was a bit dirty. The inside of the trunk is spotless. The car I bought was used by an old lady and spent most of it's life in a warm garage. Otherwise in Sweden Golf MK5 is rost buckets.

<A force test with 12V is one of the first things I'd do. But I'd feed the 12V in at the control module. If it unlocked you'd instantly know that the wiring between the module and the lock was <good. I don't know what voltages you should get on all the pins off the top of my head. I'd expect the pin with 11.5V to be the boot light switch though. And if you have a brown wire, that <will almost certainly be the earth/ground. So linking the 11.5V pin to the earth should make the boot light switch on.
Hmm then the follow up question is where is the control module located? Inside the lock then or? And what pin should I force 12v to, don't I short it if I put 12 directly to the brown ground pin?

What should the 4 pins do? 2 for light and 2 for opening?

<Just a though.....does the rear washer & wiper work?
Viper, viper fluid, all lights including top break light work fine. But will check if boot light is working have not done that yet, stupid of me.

// Johan